Last time I checked, Google did not support any Address Book synchronisation. I will check again tonight.

The solution for BIS users to sync seems to be SyncML. This is a standard for synchronising mobile phones with an internet database. The database can then sync with Outlook, Outlook Express, even Thunderbird. It depends on what the database is capable of.

Users will also need an online database. The two most popular ones are scheduleworld.com and zyb.com. scheduleworld.com is a small enterprise (one man band maybe) but it allows syncing with Outlook and even Google Calendar. Zyb only syncs between the phone and it's own online database (though you can sync multiple phones to it).

I have not tried the scheduleworld sync with Outlook as I don't use it.

A lot of SyncML applications don't support blackberry though which is a shame.